I totally and freely admit that I am a "morning person". When properly rested I function better in the morning and I enjoy the morning, especially early morning before the world really starts cranking.
Sometimes I am a "night owl" too, which doesn't usually go well with being a "morning person".
I prefer sunrises to sunsets, although I love them both.
My work hours are somewhat flexible, so I recently changed them from 10am-6pm to 8am-4pm. One of my core job duties requires concentration and if I start at 10, I am constantly interrupted by "urgent" emails asking for me to solve some kind of problem or other. If I'm at my desk at 8, I don't even look at email till 10 or 11 and I frequently get more work done in those two hours than I used to in a whole work day.
Washington DC area traffic sucks even more at 6:30am than it does at 9:30am. Hopefully I will be changing address soon, which will reduce that issue for me.
Ironically, leaving work at 4-something makes the ride home slightly better than leaving at 6-something.
I recently blogged about making time-related choices in our crazybusy lives and I am fortunate to have this flexibility option. People should play to their strengths and this example of doing that with some success.